Mariners vs. Reds Dunkel MLB Picks, Predictions and Prop Bets - July 21

The Seattle Mariners bring a three-game win streak into a home contest versus the Cincinnati Reds at 9:40 p.m. ET on Tuesday. Luis Castillo (3-8, 4.93 ERA) gets the start for the Mariners, who are 51-50 this season and first in the AL West. Chase Burns (11-1, 2.54 ERA) is expected to start for the Reds, who are 45-54 and fifth in the NL Central.

Per the moneyline, the matchup between the Mariners (-121) and Reds (-101) looks like a close one. The over/under in this contest is set at 7.5.

Mariners vs. Reds Odds, Game Time

• Game day: Tuesday, July 21, 2026
• Game time: 9:40 p.m. ET
• Location: Seattle, Washington
• Stadium: T-Mobile Park
• Favorite: Mariners (-121)
• Underdog: Reds (-101)
• Over/under: 7.5

How to Watch Mariners vs. Reds

• TV Channel: SEAM and CINR
• Live Stream: Fubo (Watch for free)

Bet now on FanDuel Sportsbook!

Mariners vs. Reds: Betting the Moneyline

• The Mariners have compiled a 47-39 record in games they were favored on the moneyline (winning 54.7% of those games).
• Cincinnati has come away with 28 wins in the 67 contests it has been listed as the underdogs in this season.
• Seattle has a record of 42-31, a 57.5% win rate, when favored by -121 or more by bookmakers this season.
• This season, the Reds have been victorious 20 times in 57 chances when named as an underdog of at least -101 or longer on the moneyline.
• The Mariners have a 54.8% chance to win this contest based on the moneyline's implied probability.
• The moneyline set for this matchup implies the Reds have a 50.2% chance of coming away with a victory in the contest.

Mariners vs. Reds: Betting the Spread & Total

• The Mariners have had an over/under set by bookmakers 101 times, and have combined with opponents to go over the total in 49 of those games (49-46-6).
• Cincinnati's games have gone over the total in 56 of its 99 chances.
• The Mariners have covered only 39.6% of their games this season, going 40-61-0 against the spread.
• The Reds are 53-46-0 against the spread in their 99 games that had a posted line this season.